1. Technical Field
The disclosure relates to a warm-up system for an exhaust gas apparatus in which an exhaust gas control catalyst is disposed downstream of a turbine of a turbocharger.
2. Description of Related Art
In an exhaust gas apparatus in which an exhaust gas control catalyst is disposed downstream of a turbine of a turbocharger, a high heat capacity of the turbine tends to result in a deterioration of the warm-up property of the exhaust gas control catalyst.
Known in this regard is a technique for opening a waste gate valve and conducting a bypass passage during a cold start of an internal combustion engine that is provided with a turbocharger, the bypass passage bypassing a turbine of the turbocharger, and the waste gate valve disposed on the bypass passage. By this technique being employed, some exhaust gas flows into an exhaust gas control catalyst through the bypass passage for warm-up of the exhaust gas control catalyst once the bypass passage is conducted during the cold start.
Japanese Unexamined Patent Application Publication No. 2001-050038 (JP 2001-050038 A) discloses an internal combustion engine which is provided with an exhaust gas passage switching valve disposed in a merging portion at which a bypass passage and an exhaust gas passage are merged, and which is provided with a turbocharger and the bypass passage bypassing a turbine of the turbocharger. In the internal combustion engine that is disclosed in JP 2001-050038 A, the exhaust gas passage switching valve is controlled, such that the turbine side the exhaust gas passage is fully closed and the bypass passage is fully opened, when an exhaust gas control catalyst disposed on the exhaust gas passage and provided downstream of the switching valve is inert. As a result of this control, nearly 100% of exhaust gas flows into the exhaust gas control catalyst through the bypass passage.